compat: Use >>substrings: String and (Sring withAll: Array)

In Pharo Object>>#asString is not doing what Array>>#asString is
doing in GST. Avoid the issue and use the String>>#withAll: selector.

Pharo needs a string for the >>#subStrings: routine. So let us create
a string here to ease porting.

OsmoCtrlGrammar.st

@@ -137,7 +137,7 @@ CtrlTrap subclass: CtrlLocationTrap [
 
     location: aLoc [
         <category: 'private'>
-        location := aLoc substrings: $,.
+        location := aLoc substrings: ','.
         location size = 8 ifFalse: [
             ^ self error: 'Failed to parse location'.
         ].
@@ -274,6 +274,6 @@ CtrlGrammar subclass: CtrlParser [
     ]
 
     notSupported [
-        ^ super notSupported => [:nodes | CtrlCmd with: nodes asString]
+        ^ super notSupported => [:nodes | CtrlCmd with: (String withAll: nodes)]
     ]
 ]

SCCP.st

@@ -214,7 +214,7 @@ Object subclass: SCCPGTI [
             split removeLast.
         ].
 
-        ^ split asString.
+        ^ String withAll: split.
     ]
 
     SCCPGTI class >> formatAddr: aNumber on: data [